This invention relates to methods and systems for protecting buildings from subsurface gases.
Buildings are often erected on sites from which subterranean gases are vented to ambience. These gases can be hazardous to human health. Exemplary of such toxic gas are radon, benzene and chlorine. In addition to toxic gases, some subterranean gases are explosive such as methane and sewer gases that are outgassed from landfills and from old industrial sites. When inhabitable buildings are constructed at such sites they rarely block out these gases. Even thick concrete slab foundations are porous and have cracks through which these gases may seep into the building itself.
Heretofore attempts have been made to vent subterranean gases rising beneath buildings to the periphery of building sites. This has been done by embedding slotted conduits in the granular bed beneath the concrete foundation into which the gases may seep and be diverted from beneath the building to its periphery. This approach however has been only marginally effective as much of the subterranean gas still bypasses the conduits and seeps into the foundation.
It thus is seen that a need has long existed for a method and system for removing subterranean gases from building sites in an effective manner. Accordingly, it is to the provision of such that the present invention is primarily directed.
In a preferred form of the invention, subterranean gases are removed from a building site by drawing air from ambience and passing the air through an air permeable bed of materials located at the site as a diffused air stream. The subterranean gases become entrained in the diffused air stream which is then exhausted from the bed and removed from the site. A system usable in practicing the method has ambient air conduits interspersed between air extraction conduits embedded in an air permeable bed of materials beneath the building. The system has means for drawing air from the extraction conduits and removing it from the site.